Device and method for fractionating and / or purifying a material stream

Abstract

The invention relates to a device and a method for classifying and / or purifying a material in a housing or a vertical arrangement, wherein a starting material (AM) is fed to a housing (10) via an upper inlet (11) and successively passes through several regions (B1, B2, B3) for fractionation and / or purification in the direction of fall (G), wherein in a first region (B1) impurities are separated from the starting material (AM) as a first fraction (F0) and the remaining starting material (AM) passes through at least two sieves (3, 5) of the regions (B2, B3) arranged in the direction of fall (G), wherein each sieve (3, 5) separates at least one fraction (F1, F2, F3, F4) from the starting material, wherein the material is transported on the screens (3, 5) in the same transport direction (6), and wherein the screen passage between the first and second screens (3, 5) or the second and third regions (B2, B3) moves at least partially counter to the transport direction (6). In addition to a general device and a general method, a preferred embodiment is intended to enable optimal fractionation or pre-cleaning of pre-crushed waste wood during the recycling of waste wood (1644).

Description

[0001] The invention relates to a device for fractionating and / or purifying a material stream according to claim 1. The invention relates to corresponding methods according to claims 15 or 16.

[0002] The invention further relates to a device and a method for fractionating material streams, in particular pre-crushed mixed materials which may contain impurities.

[0003] Such devices are used industrially to classify solids into different fractions according to defined criteria, such as density, inertia, and size. Typically, in addition to similar materials, mixtures are also classified, for example, in recycling, to obtain pure fractions. The implementation of classification processes and corresponding devices are demanding and maintenance-intensive systems in 24 / 7 operation or in large-scale industrial applications (see US Pat. No. 5,749,471 A).

[0004] Such systems are available in a wide variety of designs and are generally familiar in the recycling industry. For example, plastics and metals are separated from returned broken bottles in the recycling cycle, the fragments are sorted by glass type and color, if necessary, and then remelted.

[0005] In the production of material boards based on lignocellulose-containing materials, foreign substances such as silicates, sand, dust, but also metals, plastics and other foreign substances, especially in waste wood recycling, are often found, which must be separated before the cleaned material can be used in large-scale industrial plants for the production of material boards, plastic boards or mixed boards.

[0006] A riser classifier is typically used for material to be recycled. This system involves an airflow passing through a substantially vertical shaft against the force of gravity. Heavier material is not carried by the airflow and falls downwards, whereas lighter material is discharged at the top of the shaft. The material to be classified is generally fed in from the side of the airflow. In addition to the basic physical principle, a zigzag air classifier is typically used in the technological field of air classification for lignocellulosic materials, resulting in improved separation efficiency. This air classifier contains channels that guide the airflow in a zigzag pattern and can ensure repeated redirection of the airflow and the materials to be classified.

[0007] In a special cleaning process, WO 2023 046 989 A2 or WO 2023 046 990 A2 describe ways in which material flows can be divided in recycling and optimized for recycling. In this process, two material flows of solid wood and already compressed wood are produced from a shredded material flow of waste wood.

[0008] The object of the present invention is to create a device and a method that enable optimal classification and / or purification of mixed materials in the smallest possible space, particularly with regard to the possibility of recycling waste wood. In an extension of this object, it should be possible to implement a contaminant removal system that can significantly reduce the volume or quantity of material to be cleaned in air sifters, thus also reducing the necessary air circulation, which entails expensive construction and operation costs.

[0009] The utilization of material flows should also be facilitated in an advantageous manner by classifying or fractionating a starting material in such a way that the further utilization can be optimally adapted to the fractionated material flows, in particular with regard to subsequent comminution devices for obtaining predetermined grain sizes.

[0010] The solution to the problem for the device consists in the combination of features according to claim 1.

[0011] The solution is achieved by constructing a device for fractionating and / or cleaning a material stream in a housing or a vertical arrangement, - wherein, after an upper inlet for the starting material, several areas for separating different fractions from the starting material are arranged successively in the direction of fall; - wherein in a first region in or after the inlet a contaminant separator is arranged for separating a first fraction, preferably ferrous metal; - wherein a first sieve for separating a second fraction of oversize particles is arranged in the second region; - wherein a second sieve is arranged below the first sieve in a third region for separating at least a third fraction from the sieve passage of the first sieve; - whereby the two superimposed sieves have a similar transport direction for the material on the sieves and - wherein a transfer device for at least partially transporting the sieve passage from the first sieve against the transport direction of the first sieve or sieves is arranged between the two sieves and / or the second and third region.

[0012] The device and the corresponding method advantageously make it possible to clean a mixed fraction that has been pre-crushed before it enters a secondary shredder for recycling. Secondary shredding has the disadvantage that materials with the existing target grain size are further shredded. This ties up shredding capacity and, on the other hand, reduces the quality of the mixed fraction for further recycling. In addition, the mixed fraction typically contains fine and very fine particles, as well as contaminants from other materials, which further increase wear during secondary shredding.

[0013] The present method and device are therefore generally used when a mixed fraction has been pre-crushed and needs to be crushed again to a suitable grain size for further use in industrial processes.

[0014] In a variant optimized for the solution, preferably for waste wood, the preparation of the starting material for the device and the process is carried out as follows: - iron metal is separated using a magnetic drum, - oversizes are separated using a disc screen, - using a roller screen, three fractions are produced from the sieve passage of the disc screen, whereby - the fine material is sent for separate recycling or discharged, as it usually contains the smallest foreign matter or mineral dust, - the material with the desired target grain size is fed into the planned recycling cycle and - the enriched material with a grain size between fines and the target grain size is subjected to further cleaning or screening, for example a stone separator, because it is enriched with foreign or interfering substances.

[0015] Advantageously, the enriched material can be more easily purified and freed from foreign or contaminants. The finally purified fraction is then usually added to the material of the desired target grain size.

[0016] In some recycling cycles, it may be necessary to re-comminute or mechanically and thermally digest the target particle size. It is advantageous to remove any fines, dust, mineral components, and the like from the mixed fraction before this comminution or digestion, which significantly increases the service life of downstream machines.

[0017] The term target grain size refers to the result of the process and the device and a material that is suitable for further use and, particularly preferably, is sufficiently (pre-)cleaned.

[0018] During the separation process in the third section, the roller screen, four or more fractions can be formed. For example, another fraction may already correspond to a specified grain size, which no longer requires grinding and / or is directly usable. This can be fed via a bypass for direct recycling, i.e., a material stream of the crushed target grain size from the first screen.

[0019] In addition to the recycling application, the solution also succeeds in requiring minimal space by forming a single functional unit (magnetic drum, disc screen, roller screen, and preferably a stone separator), which significantly reduces the investment costs for the building / land. Furthermore, by utilizing gravity (material falls directly from the first screen to the second screen), conveyor technology between the screens is generally not required, which can significantly reduce the investment costs for machinery.

[0020] Ultimately, it is now possible to adapt the previously required shredding capacities. Wear and tear is significantly reduced, and only material that requires shredding for recycling is shredded. Regular maintenance requirements and thus downtime are also significantly reduced.

[0021] The invention understands and defines the terms used essentially but not exclusively or conclusively as follows: A material stream usually consists of loose or free-flowing material and has the characteristics of a mixed fraction. The mixed fractions can essentially be divided into fractions, oversize material separated, dedusted and / or sorted. Oversize material (screen residue according to DIN 66160) is generally a grain size that does not pass through the mesh size of the screen and can be separated as a separate fraction. In addition to the weight, optional additional force introductions and the specified mesh size are crucial for the screening effect. In addition to static screening surfaces, roller or roll screens can also be used, which are characterized by a large number of parallel arranged rollers / rollers. The mesh size results from the constant or variable openings between the rollers or their structures, such as discs, elevations, knobs or the like.Known roller-type classifying devices also use flattened pyramids on their surfaces. To loosen the material to be screened, usually during accumulation conveying, spiky or angular elements can be mounted on the circumference of the rollers, for example, polygonal plates or star-shaped elements instead of round discs. The mesh size results from the interaction with the superstructures or elevations of the adjacent rollers. Especially during accumulation conveying, a classifying stratification of the demixed material flow occurs on the roller bed, for example, heavy at the bottom, light at the top, which allows an enriched fraction adjacent to the rollers (contaminants with similar good material) to be discharged via a predetermined larger gap. Such an enriched fraction can advantageously be cleaned in a targeted manner using adapted methods and thus with better selectivity in order to separate the good material.

[0022] The direction of fall essentially corresponds to the force of gravity, but can also contain vectorial horizontal components, for example in the case of a throw or an inclined sieve arrangement or through baffles.

[0023] Inlets and outlets are not necessarily limited to the housing; even within the housing, compartments such as sieves can be separated from each other. Thus, this term essentially describes the separate supply and discharge of one material from another.

[0024] The device or method may include control and / or regulation devices that properly control or regulate the device or method. Preferably, the device or method can be operated using AI (artificial intelligence) or as part of a machine-learned behavior. Possible input variables, but not limited to, are the quantity or properties of the starting material, as well as the quantity or properties of the various fractions. In particular, it may be possible to operate the individual sieves and / or the guide flaps to adjust the fractions using suitable sensors (weight, photographic grain size distribution, throughput per unit time, etc.). Advantageously, such a machine learning system is only made possible by appropriate algorithms and will only be able to deliver corresponding results after a training phase.It is common practice to create parameters or other comparative values that can be used for control or regulation.

[0025] Machine learning is particularly preferred for the enriched fraction of the second sieve.

[0026] In an advantageous manner, this control or regulation can also have an effect on the upstream or downstream areas, for example on the subsequent cleaning, screening, transport or shredding devices, right up to the control or regulation of the subsequent recycling.

[0027] Furthermore, it should be noted that the implementation of the method does not necessarily have to be carried out using the device described and, in particular, does not necessarily have to be carried out using a transfer device between the two screens.

[0028] The following features may, individually or in combination, form further advantageous measures in connection with the device or method: It is possible to assign a screening device to at least one fraction outlet for separating another fraction and / or for cleaning the fraction. These screening or cleaning devices can preferably be magnetic drums, magnetic cascades for ferrous metals, eddy current separators for non-ferrous metals, heavy-material separators (stones, glass, metals), or light-material separators (films, lint, fibers, textiles). These cleaning devices can also be used in the first area of the process or device.

[0029] Alternatively or cumulatively, a vibrating screen, a disc screen, a roller screen, an air sifter, and / or a throw screen can be arranged as the first screen and / or second screen. In addition to these screens, screens that can distinguish measurable physical properties of the starting material or the previous screening pass are also suitable.

[0030] Preferably, a magnetic drum for metal separation, a non-ferrous metal separator, an eddy current separator, an air classifier, a sensor-based separation device and / or a heavy material separator can be arranged as a contaminant separator for separating the first fraction.

[0031] The transfer device can be a conveyor belt, a linear conveyor, a pneumatic conveyor, or guide plates inclined to the direction of the screen passage. The arrangement of a transfer device can advantageously significantly minimize the required installation space, because the required screens are not spread out over the entire surface but are arranged in tiers. The optionally unidirectional transport direction of the screens is particularly advantageous, allowing for a favorable design of the outlet openings and simple further processing or forwarding of the individual fractions.

[0032] Advantageously, the first screen and the second screen can be arranged essentially directly below one another. Depending on the design, a horizontal overlap of more than 50%, most preferably more than 75%, is also conceivable. The overlap enables an optimal arrangement of the outlets or may be technically necessary due to the design-related configuration of different screens.

[0033] Preferably, at least the second screen is designed to discharge different fractions along the transport direction, which are preferably assigned to different outlets. Furthermore, the outlets do not have to discharge across the entire width, but can also bundle the fractions and discharge them laterally to optimize the installation space.

[0034] In one embodiment, at least one movable control flap, preferably perpendicular to the transport direction, can be arranged below the sieves. This control flap is suitable for adjusting the ratios of the different fractions to one another or for adjusting the properties of the fractions. The control flaps can also be arranged in a vibrating manner if necessary to prevent material from accumulating in inclined positions.

[0035] In a further preferred embodiment, a disc screen, a roller screen, or a star screen is arranged as the first screen in the second area, and a roller screen is arranged as the second screen in the third area. In this configuration, the first screen is particularly well suited for sorting large volumes of oversized material in the material flow and, if necessary or intended, simultaneously performing a classifying pre-screening along the transport direction. The oversized material is generally fed again to the pre-shredding stage or a crusher so that it can be converted to the specified grain size for later recycling.

[0036] A disc screen preferably consists of parallel rollers on which axially spaced discs are arranged. The discs can be round or shaped, but square, serrated, or star-shaped discs are also conceivable. These are generally suitable for loosening the incoming material or transporting it in the direction of transport. Preferably, the discs of adjacent rollers mesh with each other.

[0037] In addition, a roller screen can consist of rollers arranged parallel to one another, with raised surfaces. These raised surfaces preferably mesh with the adjacent rollers or are spaced at a predetermined distance. Particularly preferably, the raised surfaces consist of flattened pyramids.

[0038] Preferably, the disc screen and / or the roller screen can form a sifting effect from fine to coarse along the transport direction. This can be easily achieved, for example, by adjusting the spacing between the discs in a disc screen or by adjusting the spacing between the rollers in a roller screen.

[0039] In a specific embodiment, rollers with essentially equal spacing and / or elevations can be arranged in one or more regions of the roller screen for screening a fraction. Preferably, a larger distance is arranged between two of these regions to discharge a layer of the material lying on the rollers. This layer can be a layer enriched in foreign matter or impurities. As a rule, this layer forms adjacent to the rollers and has similarly large and / or heavy particles that are enriched with further impurities, and the distance between the regions is operatively connected to a separate outlet for discharging a separate fraction.

[0040] Preferably, at least one outlet for discharging a fraction is operatively connected to a classifier or a heavy-material separator for producing a post-cleaned fraction. This can be implemented directly in the housing or, preferably, in the adjacent vicinity. Advantageously, it may be possible to combine the post-cleaned fraction with a fraction of neighboring grain size.

[0041] Alternatively or cumulatively, at least one outlet for discharging a fraction, preferably an outlet for oversize particles from a screen, can be operatively connected to a comminution device for further recycling. This comminution device is typically used in process engineering to reduce the classified and, if necessary, cleaned material to a specified grain size for subsequent recycling. This is done, for example, to reduce wood chip sizes when recycling waste wood to particle or fiber sizes for use in the manufacture of composite panels (MDF, OSB, particle board, etc.) or in plastics production when recycling recycled plastic.

[0042] The solution to the problem for a method consists in the combination of features according to claim 15.

[0043] In this method, for classifying and / or cleaning a material in a housing or a vertical arrangement, a starting material is fed into the housing via an upper inlet. The material is successively passed through several regions for fractionation and / or cleaning in the direction of fall, wherein in a first region impurities are separated from the starting material as a first fraction and wherein the remaining starting material is fractionated by at least two sieves of the further regions arranged in the direction of fall, wherein each sieve separates at least one fraction from the starting material, wherein the material is transported on the sieves in the same transport direction and wherein the sieve passage between the first and second sieves or the second and third region moves at least partially against the transport direction.

[0044] The solution to the extended problem consists in the combination of features of the method according to claim 16.

[0045] In this process for the processing of waste wood, the starting material, pre-shredded waste wood or a comparable mixture with wood components is cleaned of ferrous metals in the first area, screened in the second area with a disc screen, preferably classifying along the transport direction, and the oversize grain is discharged as a fraction via a separate outlet, wherein in a third area below the second area in the same transport direction the screen passage of the first screen reaches a roller screen of the third area in the direction of fall and is separated there into at least three fractions and fed to at least three separate outlets, wherein in the transport direction the first fraction of the third area has a finer screen passage than the other fractions of the third area,the second fraction of the third area contains wood chips enriched with impurities and / or foreign substances and the third fraction of the third area contains wood chips that can already be further recycled.

[0046] Preferably, in one of the above processes, at least the second fraction containing the impurities and foreign matter can be passed through a screening device and / or a cyclone to remove the impurities and / or foreign matter. It can then be provided to add this cleaned fraction to the material flow of the third fraction for further utilization, preferably further comminution. Advantageously, an optimal fraction with maximum wood chip size for further utilization or comminution was created here. The smaller wood chips were separated into a separate fraction with similarly sized impurities and were advantageously freed from dust or other smaller mineral foreign bodies. The cleaning of the second fraction of the third area is reliable and easy to carry out and can, for example, be easily removed if a heavy-duty and / or light-duty sifter is used, in which stones, sand orLint, fibers, or films can be removed. This second fraction can then either be recycled directly, depending on its grain size, or fed for shredding together with the oversize grain from the second screen or the corresponding adjacent third fraction.

[0047] Such comminution can also be a thermal-mechanical digestion, for example in a digester and / or a refiner.

[0048] In the method, it is preferably provided that the oversize grain of the first sieve is fed to a (post-)comminution, wherein preferably the crushed oversize grain is fed again to the method and / or the device or the crushed oversize grain is fed to the third fraction of the third region.

[0049] Particularly preferred as the starting material is shredded or broken recycled wood with a grain size of up to 300 mm for a first edge length, up to 400 mm for a second edge length, and up to 500 mm for a third edge length. Such starting material is usually available when waste wood is pre-broken in a drum chipper or a similar device.

[0050] Proposed process features usually require technical equipment for implementation and are accordingly also suitable for the device; vice versa, this also applies to the process engineering implementation of device features.

[0051] Further advantageous measures and embodiments of the subject matter of the invention emerge from the subordinate claims and the following description with the schematic drawing.

[0052] The drawing shows a schematic side view of the device 1 with a housing 10 having areas B1, B2, and B3 arranged therein in the direction of fall G. In a first area B1, the starting material AM passing through the inlet is guided past a contaminant separator 2. This ensures that, for example, ferrous metal EM reaches an outlet 12 as a separate fraction, while the remaining material in the housing falls into the second area B2. In the second area B2, a first screen 3 is arranged, which transports the remaining material in the transport direction 6 and screens it in the process. With optional classifying screening, preferably first finer and then stronger material is discharged as a screen passage towards the third area B3. The oversize grain from screen 3 reaches its own outlet 16 as fraction F4.The oversize material can either be subjected to coarse crushing and optional cleaning and then returns to the device 1 via inlet 11.

[0053] Before the screening passage of the first screen 3 reaches the second screen 5 in the third area B3, the screening passage is shifted against the transport direction 6 of the screens. This ensures a compact design and simultaneously optimizes the screening process on the second screen 5. For shifting against the transport direction 6 of the screens, a transfer device 4 can be provided which actively or passively moves the material against the transport direction 6. Passive devices include, for example, guide plates which may be assisted by vibration. Active devices include conveying devices not shown, such as conveyor belts or linear transfer devices or throwing rollers which accelerate the material. However, it is particularly preferred if the screening passage is shifted in sections, especially in the case of a classified screening passage along the transport direction 6, in order to avoid an accumulation of screening passages at the beginning of the second screen 5.

[0054] In the exemplary embodiment according to the drawing, the screening passage is preferably divided into three fractions by the second screen 5 in the third region. At the beginning of the screen 5, in the transport direction 6, a first fine fraction F1 is separated. This is followed by a second fraction F2, preferably enriched with impurities. A third fraction F3 can be formed, as shown in the drawing, as oversize particles from the second screen 5 or (not shown) as a third screening passage. The number of fractions is not limited; in particular, screen types other than perforated screens are capable of forming a multitude of different fractions, for example, actively driven roller or cylinder screens.

[0055] Fractions F1, F2, and F3 are fed to or directed through separate outlets 13, 14, and 15, respectively. The outlets do not necessarily discharge the fraction from the housing 10, but should be understood as directing or guiding these fractions to the screen 5 as independent material streams that cannot be mixed with other fractions.

[0056] Below the second screen 5 or between the individual outlets 13, 14, 15, control valves 9 can be arranged, which can adjust the screen passage in the boundary areas between the individual fractions F1, F2, F3. These valves can be adjusted manually or via adjusting means and corresponding control or regulating devices (not shown). The drives, adjusting means, control or regulating devices not shown will be independently recognizable and implemented by a person skilled in the art, provided they are necessary for the operation of the device and for carrying out the process.

[0057] It may be provided that the first or finer fraction F1 of the second sieve 5 is subjected to thermal recycling, since dust, fine dust or mineral fractions cannot usually be recycled or fed into a recycling system.

[0058] Preferably, the second fraction, comprising coarser materials and generally also other foreign or impure substances, is fed from the outlet 14 to a further cleaning or screening device 7, in which the foreign and impure substances can be separated. This separation is preferably carried out within the housing or at least directly adjacent thereto. If an air classifier is used as the screening device 7, a cyclone 8 can be connected downstream. The cleaned fraction F2' can finally be fed to a separate recycling device 17 or, preferably, to the next larger fraction F3, in order to feed them together to the planned recycling, preferably in a recycling system.

[0059] An exemplary utilization 17 in the case of waste wood recycling would be that pre-crushed starting material AM is fractionated and / or cleaned by the process or device, and in accordance with the requirements for the production of material boards, such as chipboard or fiberboard, is crushed in the utilization 17 to a predetermined grain size, glued in a subsequent gluing device, and pressed in a pressing device under pressure and temperature.

[0060] In an advantageous manner, the simple pre-cleaning or its fractionation enables a correspondingly effective utilization of the recycling 17 or the possibly necessary comminution 1644. List of reference symbols: P1644DE 1 device 2 contaminant separators 3 Sieve (first) 4 Transfer facility 5 Sieve (second) 6 Transport direction 7 viewing device 8 Cyclone 9 control flaps 10 housings 11 Entrance 12 Outlet (EM) 13 Outlet (F1) 14 Outlet (F2) 15 Outlet (F3) 16 Outlet (F4) 17 Recycling B1 area B2 area B3 area G Fall direction AM starting material EM ferrous metal F0 Fraction F1 faction F2 faction F2' fraction (purified) F3 faction F4 fraction (oversize)

Claims

[1] Device for fractionating and / or purifying a material stream in a housing or vertical arrangement; 1.1 wherein, after an upper inlet (11) for the starting material (AM), several areas (B1, B2, B3) for separating different fractions (F0, F1, F2, F3, F4) from the starting material (AM) are arranged successively in the direction of fall (G); 1.2 wherein in a first region (B1) in or after the inlet (11) a contaminant separator (2) for separating a first fraction (F0), preferably ferrous metal (EM), is arranged; 1.3 wherein a first sieve (3) for separating a second fraction (F4) of oversize particles is arranged in the second region (B2); 1.4 wherein a second sieve (5) for separating at least a third fraction (F1, F2, F3) from the sieve passage of the first sieve (3) is arranged below the first sieve (3) in a third region (B3); 1.5 wherein the two superimposed screens (3, 5) have a similar transport direction (6) for the material (M) on the screens (3, 5) and 1.6 wherein a transfer device (4) for at least partially transporting the sieve passage from the first sieve (3) counter to the transport direction (6) of the sieves (3, 5) is arranged between the two sieves (3, 5) and / or the second and third region (B2, B3). [2] Device according to claim 1, characterized by that at least one outlet (13, 14, 15, 16) of the fractions (F1, F2, F3, F4) is assigned a screening device (7) for separating a further fraction and / or for cleaning the fraction (F1, F2, F3, F4). [3] Device according to at least one of the preceding claims, characterized by that a vibrating screen, a disc screen, a roller screen, an air sifter and / or a throwing sifter is arranged as the first screen (3) and / or second screen (5). [4] Device according to at least one of the preceding claims, characterized by that for separating the first fraction (F0) a magnetic drum for metal separation, a non-ferrous metal separator, an eddy current separator, an air classifier, a sensor-based separation device and / or a heavy material separator is arranged as a contaminant separator (2). [5] Device according to at least one of the preceding claims, characterized by that a conveyor belt, a linear conveyor, a pneumatic conveyor, or guide plates inclined to the direction of fall of the screen passage are arranged as the transfer device (4). [6] Device according to at least one of claims 2 to 5, characterized by that the first sieve (3) and the second sieve (5) are arranged substantially directly below one another and preferably have a horizontal overlap of more than 50%, most preferably more than 75%. [7] Device according to at least one of the preceding claims, characterized by that at least the second sieve (5) is suitable for delivering different fractions (F1, F2, F3) along the transport direction (6), which are preferably assigned to different outlets (13, 14, 15). [8] Device at least according to the preceding claim, characterized by that below the sieves (3, 5) at least one movable control flap (9) is arranged, preferably perpendicular to the transport direction (6), which is suitable for adjusting the ratios of the different fractions (F1, F2, F3) to one another or for adjusting the properties of the fractions (F1, F2, F3). [9] Device according to at least one of the preceding claims, characterized by that in the second area (B2) a disc screen, a roller screen or a star screen is arranged as the first screen (3) and in the third area (B3) a roller screen is arranged as the second screen (5). [10] Device according to claim 9, characterized by that a disc screen consists of rollers arranged parallel to one another, on which disks are arranged at an axial distance from one another and the disks of the adjacent rollers preferably mesh with one another and / or that a roller screen consists of rollers arranged parallel to one another, in which elevations are arranged on the surfaces and these elevations preferably mesh with the adjacent rollers or have a predetermined distance. [11] Device according to claim 9 or 10, characterized by that a sifting effect from fine to coarse is arranged in the disc screen and / or the roller screen along the transport direction (6). [12] Device according to at least one of the preceding claims 9 to 11, characterized bythat in one or more areas of the roller screen, rollers with substantially equal spacings and / or elevations are arranged for screening a fraction, and that preferably between two of these areas there is a larger distance for discharging a layer of the material lying on the rollers, wherein the layer adjacent to the rollers is enriched with large and / or heavy particles and other impurities and the distance between the areas is operatively connected to a separate outlet for discharging a separate fraction. [13] Device according to at least one of the preceding claims, characterized by that at least one outlet for discharging a fraction is operatively connected to a classifier or a heavy material separator for producing a subsequently cleaned fraction and is preferably combined with the fraction adjacent in terms of grain size. [14] Device according to at least one of the preceding claims, characterized by that at least one outlet for discharging a fraction, preferably with an outlet for an oversize grain of a sieve, is operatively connected to a comminution device for further utilization. [15] Method for classifying and / or purifying a material stream in a housing or a vertical arrangement, wherein a starting material (AM) is fed to a housing (10) via an upper inlet (11) and successively passes through several regions (B1, B2, B3) for fractionation and / or purification in the direction of fall (G), wherein in a first region (B1) impurities are separated from the starting material (AM) as a first fraction (F0) and the remaining starting material (AM) passes through at least two sieves (3, 5) of the regions (B2, B3) arranged in the direction of fall (G), each sieve (3, 5) separating at least one fraction (F1, F2, F3, F4) from the starting material, wherein the material is transported on the sieves (3, 5) in the same transport direction (6) and wherein the sieve passage between the first and the second sieve (3, 5) or the second and the third region (B2, B3) moves at least partially counter to the transport direction (6). [16] Process for the processing of pre-shredded waste wood, preferably according to the preceding process claim or in a device according to claim 1, characterized bythat as starting material (AM), a pre-shredded waste wood or a comparable mixture with wood components is cleaned of ferrous metals (EM) in the first region (B1), screened in the second region (B2) with a disc screen, preferably classifying along the transport direction (6), and the oversize grain is discharged as fraction (F4) via a separate outlet (16), and in a third region (B3) below the second region (B2) in the same transport direction (6), the screen passage reaches a roller screen of the third region (B3) in the direction of fall and is separated there into at least three fractions (F1, F2, F3) and fed to at least three separate outlets (13, 14, 15), wherein in the transport direction (6), the first fraction (F1) of the third region (B3) has a finer screen passage than the other fractions (F2, F3) of the third region (B3),the second fraction (F2) of the third area (B3) contains wood chips enriched with impurities and / or foreign substances and the third fraction (F3) of the third area (B3) contains pure usable wood chips. [17] Method according to one of claims 15 or 16, characterized by that at least the second fraction (F2) with the interfering and foreign substances is passed through a screening device (7) and / or a cyclone (8) for cleaning from the interfering and / or foreign substances and preferably the cleaned fraction (F2') is fed to the material flow of the third fraction (F3) for further utilization, preferably further comminution. [18] Method according to one of claims 15 to 17, characterized bythat the oversize grain of the first sieve (3) is fed to a comminution, wherein preferably the crushed oversize grain is fed again to the process and / or the device or the crushed oversize grain is fed to the third fraction (F3) of the third region (B3). [19] Method according to claim 16, characterized by that shredded or broken recycled wood with a grain size of up to 300 mm for a first edge length, up to 400 mm for a second edge length and up to 500 mm for the third edge length is used as the starting material (AM).

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